1. Field of the Disclosed Embodiments
This disclosure relates to systems and methods for using location information derived from other radios in a multi-radio device to streamline a millimeter wave (mmWave) beamforming process.
2. Related Art
With the proliferation of wireless devices of all types running increasingly sophisticated applications, the demand for available bandwidth has increased dramatically. Communications in the millimeter wave (mmWave), e.g. 60 GHz region of the frequency spectrum have emerged as a unique solution to the need for increased bandwidth for a number of reasons. Transmitting, for example, in the 60 GHz frequency range offers extremely high data throughputs as a result of the ultra-wide bandwidth available. A tradeoff is that communications in this frequency range are highly directional with directional antenna beam forming arrays being required to sustain reasonable transmission distances based on the atmospheric absorption of the transmitted RF energy.
Wireless communications in the 60 GHz frequency range experience a high level of atmospheric radio frequency (RF) energy absorption. Understanding that the transmitted RF energy in this frequency region would be quickly absorbed by oxygen molecules in the atmosphere over long distances, wireless technology developers focused on this characteristic as a benefit for certain applications. Previously, the high levels of atmospheric absorption and resultant range limitations were viewed as rendering mmWave technologies unsuitable for certain wireless applications. As there emerged a need for short-range high data throughput transmission paths, however, mmWave technologies, and particularly 60 GHz mmWave systems, emerged as a solution.
Transmitting in the mmWave region of the RF spectrum results in a fairly focused beam as compared to transmitting in lower frequency ranges. An ability to provide secure, straight-line, high data rate communications is a significant plus. This is balanced by the need to establish and maintain directional beam communication with a receiving device, such as a mobile client device with which a mmWave source is communicating. The beamforming effort itself requires significant time and a certain amount of computing overhead to complete.
Simply put, the higher attenuation for mmWave transmissions, particularly in the 60 GHz frequency range, results in shorter transmission ranges. Directional communication with use of highly directional antennas is used to concentrate the energy in a narrow transmission beam in one specific direction. This directing of the RF energy results in a reasonable increase in the communication range between mmWave transmitter and receiver devices.
Directional communication relies on beamforming mechanisms or schemes, in which the two devices find the relative direction between one another and adjust their antenna transmit/receive patterns such that the RF energy is concentrated in the direction of the strongest path between the devices, normally a line-of-sight (LOS), or straight line, transmission path between the devices.
Those of skill in the art recognize that the term “beamforming” refers to a class of well-known signal processing techniques used in certain antenna arrays for manipulating directional signal transmission or reception. One technique is to combine elements in the particular antenna array in a way that signals at particular angles experience constructive interference, while other signals experience destructive interference. Beamforming, therefore, takes advantage of interference to change the directionality of the array. Beamforming can be used at both the transmitting and receiving ends in order to achieve spatial selectivity. In initially attempting to establish the communication link through the beamforming process, each of a pair of wireless communication devices conventionally transmits a sequence of beamforming training frames to attempt to determine appropriate antenna system settings for both transmission and reception.
The first problem to resolve is to establish some relative direction between the pair of wireless communicating in order to determine the direction in which to exchange the training frames. Conventionally, this problem of finding a relative direction for communication between the devices is solved by a combination of mechanisms known as “sector level sweep” and “beam refinement.” The sector level sweep provides a wide area scan in which one device transmits data packets in one direction after another and relies on the feedback received from the an other device to ascertain a direction in which to focus the beam refinement effort. The beam refinement effort then involves further data frame exchanges to refine the antenna settings at either, or both, of the pair of wireless communicating devices as a precursor to data transmission across a mmWave communication link between the devices.
The beamforming protocol, as outlined above, may be a lengthy process, particularly for devices that have a large number of antennas. This process adversely impacts data flow across the mmWave communication link.
Current commercially-available hand-held wireless communicating devices such as, for example, smartphones, tablets, PDAs and the like, are able to access commercially-available wireless networks in the licensed spectrum for cellular telephone communication and other purposes, as well as accessing local wireless access points with integral wireless receivers in the wireless communicating devices for short range communication in the unlicensed Wi-Fi spectrum. A single wireless communicating device is able to employ separate radios to make use of separate and diverse communication paths or links as a multi-radio communicating device combining the benefits of the communication technologies in a seemingly integrated manner to benefit the user of the wireless communicating device. These individual wireless communication devices have capabilities to access these differing network technologies that include communications that are broadcast omnidirectionally.